1. Preheat the oven to 180°C.
2. Slice the sweetpotatoes and spread them evenly on a tray lined with baking paper. Brush with the olive oil and bake for 25 minutes on the middle rack. Then leave to cool for 5 minutes.
3. Using two forks, gently press in the flesh so that the sweetpotatoes are slightly mashed but still retain their shape. Brush with the melted butter and sprinkle with garlic and parsley. Season with salt and pepper and top with the parmesan cheese.
4. Bake for another 15 minutes on the top rack until the parmesan begins to brown. Then serve immediately.
Preparation time: ca. 60 minutes